Smoky quartz is a rare variant of rock crystal prized for its dark translucence. This bowl or tazza is made in the form of a grotesque mask with open mouth. It is the finest in a group of four bowls in smoky quartz recorded in the 1607-11 inventory of the Habsburg Emperor Rudolf II as having been ‘brought from Milan’, where the Miseroni family had its workshop and where most of the finest rock crystal carving of this period was done. Giovanni Ambrogio was the head of the celebrated Miseroni workshop at this time.